11 endocrine 118. - Biology 118 11. ENDOCRINE PHYSIOLOGY...

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Biology 118 11. ENDOCRINE PHYSIOLOGY Everything an animal does is either initiated, modulated, or blocked by chemical regulators. AN EXAMPLE FOR OPENERS : The pancreas has beta-cells which secrete insulin in response to increased blood sugar – insulin stimulates several tissues to take up sugar for storage. Meanwhile, a decrease in blood sugar stimulates pancreatic alpha-cells to secrete glucagon – this hormone primarily stimulates the liver to release glucose into the blood for immediate use. These two peptide hormones help maintain blood glucose within tolerable limits. This system highlights a number of aspects of the endocrine system: A hormone is a chemical messenger that carries information (a signal) from one location of an organism’s body to another -- often through blood. Hormones are secreted by specific cells and tissues, called glands. Some glands have more than one function, like the pancreas, which takes part in digestion. There are also neuroendocrine cells, neurons that secrete their products into the blood. The homeostatic action of antagonistic pairs of hormones, feedback loops and different tissues talking to one another. A hormone has specific target tissues, and specific effects on target cell activity. WHAT DO HORMONES DO? Affect the synthesis/release of other hormones Influence metabolism (anabolic, catabolic) Stimulate smooth muscle contraction Affect growth Reproductive functions Osmoregulation Affect response to unexpected stimuli -- behavior, metabolism HORMONE MECHANISMS : there are up tp 50 different known hormones, and two basic mechanisms by which they can change of target cell activity. Membrane receptors
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This note was uploaded on 02/24/2011 for the course BIO 118 taught by Professor Bilgen during the Spring '08 term at University of Washington.

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11 endocrine 118. - Biology 118 11. ENDOCRINE PHYSIOLOGY...

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